Pilot ignition



slept. 3o, 1952 R. H. sHE-PPARD" PILoI IGNITION Filed Sept. 24, 1946 Patented Sept. 30, 1952 iLoIGNITIoN This invention relates to the starting of diesel engines and has for its principal object vthe provision of a method ofv initiating ignition byl'leating a minor quantity ofmixed fuel and air by passing this min-or quantityI into a l s rnallcell throughan orice of such size as notccmpletely to vaporize the fuel s othat- .when thecell disfcharges its -fuel and `air into the c :oinl'niistion chamber, the fuel will again beheated andthis Will'forrn a pilot ignition flame v so that the major charge within the combustionchamberis re'd ina desired manner.

While it might not seemso, actually'it isfound that very small dieseljengines are `more .diflicult to start than-the large engines, and an objectci the present inventionisto provide cells-1in communication with the combustion chamber 4so that the small engine can be started with lessv eiort than usual and withvv a lower compression,

thus providing smoother running at normal speeds. The,` invention is applicable to all sizes the spherical-combustion chamberfspac'el. Thfe combustion chamberblock IIlis heldin place by the usual disc IOT, orin any therdesirediashion'.

The novel feature ,of the present case is' the provision in combustionchamber insert piece I0 o fone` or preferably twofair cells each denoted as a whole bythe numeral S211". `These 'air cells havetheir common axisiriaplane through the of engines, working at any chosen pressure Yor temperature.

In my experimental work, I hate been able Ito start my smallest size engine readily .at the temn 1 perature of zero, Fahrenheit, vat which time the oil is highly viscous,` In its preferred formthe lair cell projects half way into the combustion chamber and is preferably duplicated on the opposite side, This extension givesthe highlysimportant advantage that the outside metal of the air cell is heatedand this Lpreserves the superheating of the contents of the .air cells bythe the small orice.

also centrally of thecombustion chamber;

Figure 3 is a much.enlargedfsectionthrough one of the air cells'. 'I l Figure vl is a top plan view of the combustion chamber.

Figure 5 shows a modified air cell.

The combustion chamber IU is of well-known form and is shown in my Patent No. 2,380,615, dated July 31, 1945. This block or combustion chamber is inserted into the cylinder head I I so that the center line I2 of the discharge of the injector I5 will pass through the center of the combustion chamber, the chamber itself being spherical and formed in part by the domed surface I6 in the cylinder head II. The line of discharge of the injector after passing through the center of the combustion chamber strikes the combustion jector' andis parallel -tof the ,likly center ofl lthe Icombustion A,chamber recess l I4', which plane is perpendicular'to the kcer'iter lineof discharge I2. In other worlds, the4 axsiof the aircells is'` p erpenclicular.y tofth'e, isfof the in- I-the piston 2,2. v, The preferredbform `of air cellfis shown in Fig'- ure 3, and consists ofna body 36, hayig a shoulder v3l fitting against a? corresponding circular fvsholil-t yder 32 lin the5combus'tion chamber, I0f-softhat the air cell is about equally vdivided fwith: respect t'o the margin33 oigthe spherical combustion cham` A ber'proper, i.l e. ,-I4.v .The frontendlo the aircell body fis. .reversalst -cical as shown, at 3M,0 pro.- Vide a funnelatthe center, havinganhorifice 31. -On thefwall opposite the ccnilcalgyvall, 35 isthe gconicalsurface 38.; Theangle-:zthat this-wall makeseapparently is nott criticalgand the wall couldpbeiazcurve,` but .I prefer theconical shape f-sozthattheradial ,sectionv is ,as seen inv Figure '3, thattis, Aextending divergently from'gtheaxis.' rThe .,inclosed portion ,of 'the radial isectiondncreases rather .rapidly tothel roundedpend 39..,5 I The fad-- vantage of such afstructure isthat it carries heat away V`from' theori'-lcerS'I rather rapidly butre- Vtains the'heat atithe thickerfportion, bearing in 'mind that',` since the cell 'projects into the combustio'n'chamber upto the lline 33, a very cons iderablev amount of heat isv given'to the interior of thev cell by thetemperature in the combustion chamber.

' and also the air cell inserts 20 projecting into this The rear 44 of each of y combustion chamber. the air cells is therefore cylindrical as best seen in Flgure 4. I nd it convenient to make the central portion of the rear surface of the plug 43 g 3 Spherical as at 46, preferably of somewhat greater radius than the curve at and near the junction of the body 30 and the plug 43. The preferred form of the curve of the plug would seem to be a parabola, but the particular configuration of the air cell shown in Figure 3 is the best of many models that were tried out, although other models work fairly well. f

The particular engine on which this device was irst usedy isa diese-l engine only 281/1 high, 221/2 long, with a 4" stroke in a 3" bore, and

delivering 3% horsepower while turning at 180Q- R. P. M. For an engine of this size, the airell chamber is 1/4" in diameter and the diameter ofl the oriiice is twenty thousandths o f an inch,and preferably the length of the orifice is the 'saine as its diameter so, as seen Figure ?,it`s=sctif is a square. The size of the diameter is Wquite critical and a variance o f as much as two thu` sandths of aninch seribusly detracts from the operation: The 'arealU c'this Qriiice' plelfretly isf not 'd enden@ en ine eiibieieapaeiiy of iheeir ceufbu is ciiepe'ngiepi;` uppnthe veiiime of' the chamber in the cpanbusti han'ibe'r block'h'whi'ch turn var'ieslywith the vgluriie' of the engine il; yind-ei. 'rh chamber r4 which eeiiibiieiion tallesplaceisspherical; as 'pr 4 ouslyfr'ecit'd with ihiradws'Gr....'ffe ehdwii in fini' cioe case 'S1 N. iaiiiihie. l i. clai'msffor aj largr-en'gin'- ir cell diameter 'wculd' be`^ increased prop t i at'ely as would the oiifiee` damier., i fis-ailA exemples, erge-4f" fiore @reihe ine ,ce1-1 .wowd- -iaie ema-sirname@ ef a 'half ioh' andj the rlficediameter would-give Vthe space through an orifice of such size as to heat fuel and air by wire-drawing effect Without completely vaporizing the fuel, the common axis of the two orifices lying in a horizontal plane perpendicular to the line of discharge of the injector fpr'miieiepiegeeii by e conicalI` 'surface 50'. vslanci5. j 'the ro'n't curved portion572` and' threbirve- 5346i hun eiween surfaces Swami. 5laiiciws more Heat i ytof pass frfcm the 'cmbu'stion chamber-infie .the chamber of the'A 'air` ce'lllan'dl 'the a'iiffcelll body gets vfecisideifjably. hotter; but 'itis 'believed 'that 'the riowerfefciencyofl thisityperisf'due tothe factthat chamber 'gets s'o hot vthat when fit is discharged again through the-r nrifice: v5*'1, theuelicis completely vapo'ri'zed'. fAt-'rst thoughtg. this' would vseem to be' anadvantage; but practice? has Ishown extremely tiny, itis; true,. but there 'musb-.bezliquid particles-e .An exemplaar' this can readily be seen from the action of gasoline whenusedito and at lri'glitangles to a plane containing the axis of the-throat, said orifice diameters varying with the bre of the cylinder of the engine and being about .020f for a threeinch bore and a quarter inch diameter cavity, abt.045" for-a fur inch here anu agi/reif inen diameter cavity. eie. 2; Iii e. diesel engine ef the type having a cylinder block with Aa cylinder within the block,. a pistonwithin the cylinder', a cylinder head closing the ieper' the cylinder, said cylinder heed having a' pree'crhbustion chamber' thereinA and a throat leading from the 'pre-c'crnbust'ion chamber to the space the cylinderv above thepiston, and an injector' discharging inte the precombustin chamber: thecombin'ation in which an' air` cell projects inte the pre-combustinv chamber, to# gather' with an additional air' cell coaxial with the first air' cell and both air cells Drbjecjt into the preebmbusiieh chamber freiighiy"v naif 'their agci'alglen'gth so that the' ori ces 'of the air' cells are well with-in the magnfof? the preec'ombustion chamber.

RIC'H'RD" SHEPRD'.-

- REFERENCES-'CITED' The renewing references are lef ieeerd the le of this -patentz UNITED STATES A'rNTs nate'K Australia Mar'. 1-,- i945 

